Field Of The Invention
1. This invention relates generally to art of intraocular lens implantation and more particularly to a novel surgical aid including an improved surgical instrument and surgical instrument package for inserting a foldable intraocular lens into a patient's eye thru a corneal incision.
Discussion Of The Prior Art
2. The lens of the human eye is a crystalline lens which is situated behind the iris and attached to the ciliary muscle by zonules. The lens consists of an outer capsule with anterior and posterior surfaces, the lens containing a clear central matrix. This central matrix often opacifies with age and for various other reasons and thereby progressively blocks the passage of light to the retina of the eye. Eventually, the central matrix attains a degree of opacity which is referred to as a cataract. This abnormal ocular condition is corrected by removing the opacacified lens, which is a procedure known as cataract extraction, and replacing the lens by an artificial lens for focusing the light entering the eye on the retina. Intraocular lenses have gained widespread acceptance as replacements for cataracted human lenses.
The modern technique for removing the central opaque part of the lens or cataract is a procedure called phacoemulsification. In this procedure, a sophisticated ultrasonic titanium tipped instrument is introduced into the eye. This titanium tip is ultrasonically vibrated in a manner which emulsifies the opaque central matrix of the lens. The emulsified matrix is then aspirated from the eye, leaving the original posterior capsule of the lens intact with a small anterior capsular remnant. When the capsule or part of the capsule is thus left inside the eye, the procedure is called extracapsular cataract extraction. Extra capsular extraction allows the intraocular lens to be placed behind the iris either in the space known as the ciliary sulcus, that is the space immediately behind the iris and in front of the anterior capsule remnant or in a space known as the capsular bag, that is between the posterior surface of the anterior capsular flap and the anterior surface of the posterior capsule.
A cataract can be removed by this phacoemulsification procedure through an incision of 3 mm or less. On the other hand, most intraocular lenses implanted today are hard methyl methacrylate lens having a diameter of at least 6 mm and as much as 7 mm or 8 mm. Therefore, the incision used for the phacoemulsification procedure has to be enlarged to more than twice its size to allow the surgeon to implant a hard methyl methacrylate lens. Regarding the incision size, it is apparent to many leading cataract surgeons that the smaller the wound, the lower the complication rate during cataract surgery and the faster the physical and visual rehabilitation. The degree of astigmatism is also much less with the smaller wound.
The latest developments in intraocular lens technology have been in the area of deformable lenses made from silicone and hydroxyethylmethylmethacrylate materials. Intraocular lens fabricated from these materials can be deformed so that they may be inserted through a much smaller incision than those required for implantation of a hard, rigid intraocular lens. Foldable intraocular lenses of this kind and instruments for inserting such lenses into the eye are disclosed in U.S. Pat. No. 4,424,597 to Schlegel, U.S. Pat. No. 4,573,998 to Mazzoco, and U. S. Pat. No. 4,673,406 to Schlegel.
Although U.S. Pat. No. 4,573,998 to Mazzocco describes many different methods and instruments for inserting a foldable silicone lens through a small incision, these and the many other intraocular lens insertion methods and instruments which have been developed are by and large unsatisfactory. Thus, many of the instruments designed to insert a foldable lens damage the lens during insertion or are unable to fold the lens adequately to allow it to be inserted through a significantly smaller incision than that required for hard lenses.
Accordingly, there is a definite need for an improved surgical instrument for inserting or implanting a foldable intraocular lens into a patient's eye which avoids the above and other deficiencies of the existing surgical instruments for this purpose. My copending application Ser. No. 198,571 now U.S. Pat. No. 4,862,885 discloses one such improved surgical instrument for implanting a foldable intraocular lens.